This is the LEDE SDK. It contains a stripped-down version of the buildroot. You can use it to test/develop packages without having to compile your own toolchain or any of the libraries included with LEDE. To use it, just put your buildroot-compatible package directory (including its dependencies) in the subdir 'package/' and run 'make' from this directory. To make dependency handling easier, you can use ./scripts/feeds to install any core package that you need